The present invention is related to a multistage socket in which simply by means of rotating a rotary member, the size of the polygonal hole of the socket can be changed in accordance with the sizes of different nuts or bolts.
FIG. 5 shows a conventional multistage socket including a socket main body 6. The socket main body 6 is formed with a fitting hole 61. The fitting hole 61 has two parallel straight walls formed with opposite teeth 611 at equal intervals. The socket main body 6 is further formed with a through hole 62 and a retaining hole 63 symmetrical to each other in parallel to the straight walls. The multistage socket further includes a resilient member 7 made of a curled steel plate. The resilient member 7 has a central chucking slot 71. Two ends of the resilient member 7 are respectively fitted in the through hole 62 and the retaining hole 63 to bridge the resilient member 7 over-the fitting hole 61. The multistage socket further includes a movable adjustment block 8 having an inner V-shaped face 81 and an arced outer face 82. Two lateral sides of the adjustment block 8 are formed with teeth 83. A mushroom boss 84 protrudes from the center of the bottom of the adjustment block 8. The mushroom boss 84 is chucked in the chucking slot 71 of the resilient member 7. The multistage socket further includes a socket handle 9 having a fitting end 91 for fitting with the socket main body 6. The fitting end 91 is formed with a channel 92 in which the resilient member 7 and the mushroom boss 84 are clamped. According to the above arrangement, the position of the adjustment block 8 can be adjusted in accordance with the size of the nut to define a hexagonal fitting hole together with the socket main body. Therefore, one single socket wrench can have various specifications of hexagonal fitting holes adaptable to various sizes of nuts. A user can conveniently carry the socket wrench to wrench/loosen various sizes of nuts.
However, the conventional multistage socket still has some shortcomings. For example, such socket has complicated structure and is difficult to process. The resilient member is made of curled steel plate and assembled with other components. It is hard to control the precision of the assembly.